How many calories do I need?

The energy requirements of the human body vary from person to person. Essentially, there are three factors that are taken into account when computing the calorie requirement of a person.

Basal or resting metabolic rate: The basal rate is the amount of energy required by the body when it is at rest. As mentioned earlier, even while at rest, there are a number of vital functions that the body performs such as respiration, circulation, functioning of various organs, maintenance of body temperature, etc. The basal rate accounts for almost fifty five per cent of the body’s daily energy requirement.

Thermic effect of food: The body requires a certain amount of energy to digest food and absorb the nutrients that it receives. This energy requirement is called the thermic effect of food.

Physical Activity: The most obvious requirement for energy is physical activity. The actual energy requirement will vary from person to person and will be determined by factors such as lifestyle, occupation, etc. Even the minutest of physical activities such as sitting on a chair or turning the pages of a book requires a certain amount of energy.

The amount of energy required for a particular physical activity also depends on factors such as the weight o the person, and the intensity of the activity. For example, an obese person climbing up a flight of stairs requires more energy, as compared to a slimmer person climbing up the same flight of stairs. However, if the slimmer person ran up the stairs, he might require more energy than an obese person climbing up the stairs, because running is a more intense form of physical activity than walking.

In order to aid researchers and medical practitioners, most of the common occupations, have been classified as either sedentary, moderate, or heavy. While the energy requirements of two people engaged in the same activity will not be exactly the same, as illustrated earlier, it will be far more similar than two persons engaged in different activities.

The various professions that are listed under these three categories are as follows:

This list is by no means exhaustive, but it will give you a fair idea of whether you are in a sedentary profession, or one with moderate, or heavy physical activity. As you must have noticed, the professions have also been separated on the basis of sex. This is because men and women have different energy requirements even when they are performing the same activity. In case of growing children, the calorie requirement is further increased because energy is required to fuel the body’s growth.